The invention relates to a head protection equipment comprising a breathing mask, a harness enabling it to be put into place quickly on the face, and means for providing the eyes with protection against smoke.
Protective equipment that can be donned quickly is already known (EP-A-0 288 391 or U.S. Pat. No. 5,690,102), and it is intended in particular for the flight crew of passenger-carrying aircraft, the equipment being of the breathing mask type provided with a regulator for connection to a source of breathing gas under pressure (generally oxygen) together with a harness having at least one extensible strap whose ends are connected to the mask and which includes an element that can be inflated temporarily by the gas under pressure in order to lengthen the strap to a size that is large enough to enable the user to put the harness over the head, and that can then be exhausted to allow the strap to tighten, to press the mask against the face, and to hold it in place. The equipment described by way of example in U.S. Pat. No. 5,690,102 enables the pressure in the inflatable element to be adjusted in such a manner as to give it an intermediate value between the full emptying pressure and the full inflation pressure, thereby making it possible to reduce the discomfort caused by wearing the mask continuously under flight conditions where that is essential. In the equipment according to U.S. patent application Ser. No. 09/700117 (published as U.S. Pat. No. 6,470,887 B1), mechanical adjustment is substituted for pressure adjustment. Documents EP-A-0 628 325 (or U.S. Pat. No. 5,503,147) and U.S. Pat. No. 5,623,923 provide for automatic adjustment. In order also to provide the eyes with protection against aggressive agents, and in particular smoke, and without using a hood with a neck gasket, proposals have been made to fit the above-defined equipment with a transparent visor that is ventilated internally from a breathing regulator. The visor can be permanently fixed to the mask as in the equipment sold under the trademark xe2x80x9cMAGICxe2x80x9d by the assignee of the present invention (U.S. design Pat. No. 304 384) or it can be detachable so as to make the mask easier to store (U.S. Pat. No. 5,630,412). In both cases, orifices for delivering breathing gas under pressure from the regulator to the visor are provided to sweep over the visor and avoid it misting up.
Another solution for facilitating storage consists in using a visor that is flexible and foldable. Equipment with visors of that kind, for use by the US Air Force, has been marketed since 1976 by Scott Aviation under the reference MBU-2/P. That equipment comprises a nose-and-mouth mask sealed to a flexible transparent visor of polyurethane and provided with a leaktight gasket bearing against the face. Because of the presence of a face gasket, it is difficult and awkward to fold the equipment for stowage in a box; long-duration storage can damage the gasket.
The present invention seeks in particular to provide head protection equipment that surrounds the eyes and the openings of the airways, providing comfort that is equivalent to that of existing equipment, that is easily stored, and that provides sufficient protection against smoke and gases that irritate the eyes. For this purpose, the invention makes use of the fact that total gas-tightness is not necessary, since ventilation due to the breathing gas being under pressure suffices to expel smoke and irritant gases.
Consequently, the invention proposes equipment of the kind defined above, characterized by a flexible cover covering the head, fixed in leaktight manner to a sheath for limiting elongation of the single strap, or of the top strap of the harness, and fixed to the mask, said cover being transparent, at least in a portion thereof that lies in front of the eyes when the equipment is being worn.
This structure makes it possible to avoid fitting the cover with a visor face gasket of the kind that is essential in prior equipment, where such a gasket is too stiff to make it convenient to fold the equipment properly for storage purposes.
The connection between the cover on the one hand, and the mask with the strap on the other can be made completely gastight; there generally remains a gap between the face and the cover in a boundary zone behind the sealing gasket of the mask. However this gap can be made very small by disposing the straps appropriately, as explained below. Under such circumstances, pressurized breathing gas coming from the regulator via the mask leaks into the environment sufficiently to expel any smoke or irritant gases tending to penetrate towards the eyes.
The leaktight or substantially leaktight connection between the cover and the extensible strap can be provided by winding the edge of the cover around the inextensible outer sheath that is commonly provided for limiting elongation of the strap. This connection between the cover and the inextensible sheath of the strap can be provided by stitching or by adhesive, in particular.
The edge of the cover need to be long enough to avoid impeding lengthening of the strap for the purpose of donning the equipment. This edge then puckers when the strap deflates. Experience shows that shrinkage of the strap during deflation occurs for the most part in its rear portion, and thus without provoking puckering that affects the visor. It is often advantageous for the portion of the cover that is close to the mask to be made stiffer than the rear portion of the cover so as to ensure that the front portion does not pucker.
In a modified embodiment, the cover is not restricted to being a mere cap. It is extended downwards from the single strap or from the top strap in order to provide additional protection. For harness having two straps, the tubular portion of the cover beneath the top strap can be free relative to the bottom strap or it can be fixed to the sheath of the strap. In the first case it suffices for the cover to pass outside the bottom strap so that when the bottom strap inflates it spreads out the bottom portion and makes the equipment easier to put onto the head. In contrast, when it is desired for protection to be as complete as possible, it is advantageous to place the bottom portion of the cover inside the bottom strap.
The cover can be implemented in various ways, in particular as a function of the user for whom the equipment is intended and as a function of the optical quality required for the transparent portion.
In a particularly simple solution, the cover is a single piece of transparent material such as polyurethane, with a portion thereof constituting a visor. To prevent the visor-forming zone from kinking, this zone can be made thicker so as to be less flexible than the remainder of the cover.
The visor can be a single piece, or it can comprise separate eyepieces united by a thinner portion that makes folding easier for storage purposes.
Having the cover structured in this way to form a head-covering cap, has the advantage of being particularly simple and of providing a very wide field of view. The optical qualities that can be obtained are generally insufficient for a pilot. However, this solution can be adopted for other crew members of civilian or military aircraft when a small loss of precision in vision can be accepted, and this also applies for applications on the ground.
In another embodiment, the cover is of composite structure. The non-transparent portion is of a flexible fabric that is impermeable or of very low permeability, that is preferably not flammable, and that withstands high temperatures. In particular, it is possible to use the fabric sold under the trademark NOMEX, which fabric is coated to make it better proof against contaminants. The transparent portion is constituted by a flexible visor comprising a single piece or two eyepieces, made of polyurethane or some other material which can either be rigid when high optical quality is required, or else slightly flexible, and in either case the visor is fixed in leaktight manner to the fabric.
This embodiment presents the additional advantage in that the cover constitutes a cap that protects the scalp against high temperatures and possibly also protects the neck, and indeed the shoulders, when the cover has a bottom portion extending beneath the top strap.
In a modified embodiment the usual box for storing the head protection equipment is replaced by a flexible bag which can be designed to receive equally well a mask with a pneumatic harness enabling it to be donned quickly or a mask including a cover for protection against smoke.
The above characteristics and others will appear more completely on reading the following description of particular embodiments given as non-limiting examples.